1. Field of the Invention
The present invention relates to an image processing system, and more particularly to a document image processing system.
2. Description of the Prior Art
In a binary processing system for an image signal, a document sheet is prescanned to detect a document density or determine a slicing level for binarization in order to binarize the read image signal based on the detected result. In one prior art system, the slicing level is determined based on information including unnecessary information on other than a document area on a document sheet table. As a result, genuine optimization is not attained. In another prior art system, the slicing level is determined based on an average document level or the background level. In this method, too, an optimum binarization is not attained.